Logarithmic Conductivity of Cr-C nanocomposites

The evolution of the electron transport in thin films of chromium-carbon nanocomposites is studied over the temperature range 4.2-300 K by chromium concentration variation from 0.2 to 0.4. It is shown that conductivity of the nanocomposites demonstrates the power-like behavior in the two temperature intervals with a separating temperature about 20-25 K. Within each temperature interval the power exponent varies from the values close to 0 up to 0.6 and decreases with increase in Cr concentration from metal-insulator transition point. The concentration dependence of the power exponent in the low-temperature interval is characterized by the existence of the expressed minimum at Cr content close to 0.28 – 0.3. The experimental data are discussed and simulated in the model of inelastic tunneling of the electrons in amorphous dielectrics in the framework of the effective medium approximation.